Kioku Soushitsu no Okaa-san

Atsushi's father died when he was young, and since then, he has lived together with his mother, Yayoi. He loves her as a woman, but she only sees him as her son. One day he receives a call from the hospital. Yayoi had an accident and now has amnesia. When he arrives at the hospital, he introduces himself to Yayoi as her lover.